Spotted Lanternflies

It would be nice to think of spotted lanternflies as Asian equivalents to our gentle fireflies of summer evening fun, but that would be a mistake. According to Penn State, lanternflies “could be the most destructive species in 150 years.”

Adult spotted lanternfly (Walthery) CC BY-SA 4.0

Native to China and India, invasive spotted lanternflies (Lycorma delicatula) were first detected in the U.S. in 2014. But it appears they snuck in on shipments of stone, woody plants, firewood, wood products, landscaping materials, and outdoor furniture two or three years before that. [Why in the world we are shipping stones from China is beyond me…]

Today, spotted lanternflies occur in several states, and they threaten gardens and farms everywhere. There are also serious concerns about our nation’s forests.

Crops vulnerable to spotted lanternflies include apple, cherry, chestnut, grape, hops, nectarine, peach, pear, plum, and walnut. Vulnerable ornamentals include birch, maple, pine, poplar, and rose. Its favorite host is the tree-of-heaven (Ailanthus altissima), also known as Chinese sumac, and varnish tree (because of its stinky odor).

There may be more plants at risk. We don’t know yet. What we do know is this—we need to report these pests every time. Let’s learn how.

Spotted Lanternfly (Lawrence Barringer, Pennsylvania Department of Agriculture) Public Domain

Spotted Lanternfly identification

As far as bugs go, spotted lanternflies are rather pretty. They are large, mothlike bugs, approximately one inch long and an inch-and-a-half wide. Adults have a black head and grayish-brown forewings with black spots. The plump abdomen is yellowish with black and white stripes. If you see one in flight, you’ll see that they have red underwings and a white triangle in the middle of the wing. Their hindwings have a brick-and-mortar pattern around the edge of the wings.

​Spotted lanternfly lifecycle

Yellowish-brown eggs are laid in inch-long, rectangular masses on stones, smooth-barked trees, or other vertical surfaces. These egg masses are covered with a gray or yellowish-brown waxy coating and are referred to as egg cases. Each cluster contains 30–50 eggs. In spring, the eggs start to hatch. Wingless nymphs go through several developmental stages, or instars, before reaching adulthood. The first instar is black with white spots. As they develop, red spots become visible. In the final instar, the upper body is red, and you can see red wing pads if you look closely. These spotted lanternfly nymphs crawl or hop to feed on a wider variety of plants than adults. I guess as they mature, their taste buds change.

By midsummer, adults are actively seeking mates and wreaking havoc in gardens, fields, and orchards. While lanternflies can fly, they seem to prefer jumping. Eggs are laid starting in autumn and ending as winter arrives. Late season eggs overwinter unseen, and the cycle begins again in spring.

Early instar spotted lanternflies (Rkillcrazy) CC BY-SA 4.0

Young spotted lanternflies (Rkillcrazy) CC BY-SA 4.0

Spotted lanternfly damage

Spotted lanternflies are sap suckers, and they feed in large groups. Imagine the feeding power of aphids combined with the size and strength of cicadas. We may be in for some serious trouble with these guys. If that weren’t bad enough, those swarms will crawl all over you if you go outside when they’re around, like locusts. They have been likened to locusts by farmers and vineyard owners who say this pest comes in in swarms, devastates an area, and then they move on to the next feeding ground.

Spotted lanternflies use piercing mouthparts to access the sugary sap found in the phloem under the bark of trees and shrubs. Like other sap eaters, lanternflies excrete a lot of sugary waste, known as honeydew, that coats leaves and stems, creating a habitat for sooty mold and other fungal growths. These pests produce so much honeydew that it feels like a mist falling from the underside of infested trees. The combined effects of sap loss, compromised bark, and interrupted photosynthesis often lead to early leaf loss. Heavy infestations can kill a mature tree.

​Spotted lanternfly management

Adult spotted lanternflies on red maple (Rkillcrazy) CC BY-SA 4.0

Because this pest is new on the scene, there is a lot we don’t know. While spotted lanternflies have natural enemies in China, that may not be the case elsewhere. At this point, the Pennsylvania Department of Agriculture makes the following recommendations:

• Inspect vertical surfaces for eggs autumn through spring. If eggs are found, gently scrape them into a sealable plastic bag that contains some alcohol or hand sanitizer, using a credit card or some other thin tool, making sure not to scatter the eggs.
• Remove any tree-of-heaven specimens on your property.
• Infested trees can be treated with systemic pesticides and bark sprays in summer.
• Apply sticky barriers to the trunks of any potential host trees to trap nymphs.

There may still be time to eradicate spotted lanternflies from North America, but only if we all keep our eyes open and report any sightings.

I can’t stress this enough: if you see a spotted lanternfly, catch it, kill it, and report it to your local County Extension Office or Master Gardeners.